Neurologic diseases are relatively common in companion rabbits and are being identified more frequently because of owners' greater interest in providing better healthcare to their pets, better-trained veterinarians, and improved diagnostic aids. In addition, many rabbits are living longer. Also, more has been discovered about the causes and treatment of neurologic diseases in rabbits in recent years, increasing our confidence in diagnosis and possible treatment.
Signs of neurologic disease in rabbits may include behavioral changes, torticollis (head tilt or wry neck) (Figure 1), nystagmus, tremors, paresis, paralysis (generally of the hindlimbs), and seizures. Other signs include loss of skin sensation (which is not always reliable in rabbits because of their stoic nature), loss of motor control of the urinary bladder and anal sphincter, development of decubitus ulcers (possibly as a result of paresis or paralysis), and a perineum stained with feces.
1. A rabbit with torticollis and nystagmus.
An understanding of the nervous system is, of course, necessary for diagnosing and treating neurologic problems in rabbits. Neurologic conditions in rabbits can be caused by a number of factors, although most cases are a result of infection or trauma (Table 1). For example, in a study in pet rabbits in the United Kingdom, head tilt in dwarf breeds appeared to be most frequently caused by Encephalitozoon cuniculi infection, whereas in standard breeds it was more likely caused by Pasteurella multocida infection.1 Fortunately, the diagnostic procedures used in rabbits with neurologic signs are similar to those used in other companion animals:
Table 1. Common Causes of Neurologic Signs in Rabbits
- Physical examination
- Neurologic examination
- A complete blood count and serum chemistry profile
- Bacterial culture and antimicrobial sensitivity testing
- Radiography, computed tomography, magnetic resonance imaging, and myelography
- Cerebrospinal fluid evaluation
Torticollis in rabbits may be caused by the extension of P. multocida infection from the nasal cavity to the middle or inner ear through the eustachian tube, or it may arise centrally in the medulla or cerebellum.2 Rule-outs include encephalitozoonosis, and, less commonly, otitis externa, cranial trauma, listeriosis, ascarid migration, or extension of an ear mite infection.
Although you can reliably diagnose Pasteurella species infections in young rabbits with serologic testing, serology is of limited use in older rabbits because they develop antibodies to gram-negative core antigens shared by P. multocida and Enterobacteriaceae, and false positive results may occur.3 Serology in older rabbits is more useful to rule out the absence of infection than to identify infection.3 The best method for diagnosing P. multocida infection is a combination of polymerase chain reaction (PCR) on nasal swabs and serology.3